1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly to a backlight structural body which uses an external electrode fluorescent lamp (EEFL).
2. Description of the Related Art
A liquid crystal display device has been widely spreading as a display device of a television receiver set or an information terminal. Usually, in the liquid crystal display device of this type which is relatively large in size and has a screen which is required to exhibit high brightness, as a backlight structural body which constitutes an auxiliary illumination device of the liquid crystal display device, there is adopted a so-called direct-light-type backlight structural body which arranges a plurality of linear light sources on a back surface of a liquid crystal display panel thus directly radiating light from the linear light sources to the back surface of the liquid crystal display panel. Here, the term “direct-light-type” is the expression which contrasts with a so-called side-light-type backlight structural body which performs illumination by mounting a similar linear light source on a side of a light guide plate which is arranged on a back surface of a liquid crystal display panel.
In the direct-light-type backlight structural body, a cold cathode fluorescent lamp (CCFL) has been popularly used as a linear light source. In general, in the inside of the direct-light-type backlight structural body, a plurality of CCFLs is arranged in parallel. However, with respect to the CCFLs, one inverter circuit is directly connected to one or two CCFLs and hence, it is necessary to wire lines from the respective CCFLs to the inverter circuit thus requiring complicated wiring. As an example which describes such a constitution, patent document 1 described below is named.
Recently, in place of the CCFLs, an external electrode fluorescent lamp (EEFL) has begun to be used. Different from the existing CCFL, the EEFL has an electrode outside a lamp and hence, in addition to an advantage that the connection is easy, a plurality of fluorescent lamps can be connected in parallel to the inverter circuit. Accordingly, in the EEFL, by making use of this parallel connection, the connection from the respective lamps to the inverter circuit can be realized using a common line thus reducing the number of lines. Further, the number of inverter circuits which the EEFL uses is smaller than the number of inverter circuits which the CCFL uses. As examples which use such an EEFL, patent document 2 and patent document 3, described below are named.
Patent Document 1: JP-A-2002-231034
Patent Document 2: JP-A-2005-347259
Patent Document 2: JP-A-2004-164907